MarkWest Energy Partners, L.P. (MarkWest) (NYSE: MWE) and The Energy & Minerals Group (EMG) announced today the completion of the previously announced Amended and Restated Limited Liability Company Agreement (Amended LLC Agreement) for MarkWest Utica EMG, LLC (Utica Joint Venture). The Utica Joint Venture is dedicated to the development of critical midstream infrastructure on behalf of natural gas producers operating throughout the liquids-rich Utica Shale formation in Ohio.

“Due to the tremendous success of producers operating in the Utica Shale, the scale and scope of the Utica Joint Venture has expanded considerably over the course of the past year. This transaction addresses the capital requirements associated with the ongoing system expansion.”

Under the terms of the Amended LLC Agreement, EMG will increase its initial capital investment in the Utica Joint Venture from $500 million to $950 million. The additional contributions from EMG provide MarkWest with significant financial flexibility in the timing of its capital contributions to the Utica Joint Venture. The Amended LLC Agreement does not modify the ownership interest levels or quarterly distribution percentages as originally set forth between the parties.

In addition, MarkWest expects to receive a distribution from the Utica Joint Venture substantially equivalent to its short-term contribution by the end of February 2013.

In the past three months, MarkWest has successfully raised $1.5 billion in net proceeds from debt and equity transactions. In addition, MarkWest is currently undrawn on its $1.2 billion credit facility and has the ability to issue common units under its $600 million continuous equity program. These transactions, coupled with the execution of the Amended LLC Agreement, provide MarkWest with significant liquidity to fund the majority of its 2013 capital plan.

“We are pleased to announce the expansion of our relationship with EMG in the Utica Shale,” said Frank Semple, Chairman, President and Chief Executive Officer of MarkWest. “The success of our Utica Shale Joint Venture is a direct result of the outstanding drilling results by our producer customers and the execution of our full-service midstream business model in this rapidly developing resource play. Clearly, we believe that the Utica Joint Venture with EMG is creating significant long-term value for our customers and our investors.”

“Due to the tremendous success of producers operating in the Utica Shale, the scale and scope of the Utica Joint Venture has expanded considerably over the course of the past year. This transaction addresses the capital requirements associated with the ongoing system expansion.” stated John Raymond, Managing Partner and CEO of EMG. “We are pleased to further grow and support the relationship we have with the talented people at MarkWest.”